JPH0520571B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates generally to a mechanism for changing the pitch of propulsion blades in a gas turbine engine, and more specifically, to a pitch changing mechanism for fan blades in a ductless gas turbine engine. .

BACKGROUND OF THE INVENTION A gas turbine engine typically has a gas generator, which compresses air flowing backward through the engine, mixes fuel with the compressed air, ignites it, and generates a high-energy gas stream. a combustor forming a compressor, and a turbine connected to drive a rotor driven by the gas flow and driving a compressor. Additionally, many engines are located aft of the gas generator and extract energy from the gas stream to produce variable pitch blades such as those found in helicopter propulsion systems, ductless turbofan engines, and turboprop engines. There is a second turbine, called a power turbine, which drives a rotating load with a

The turbofan and turboprop mentioned above
Recent improvements to the engine have been made in pending U.S. patent application serial no.
It is a ductless fan engine as described in No. 437923. In a ductless fan engine, a power turbine includes counter-rotating rotors and turbine blades that drive ductless fan blades disposed radially relative to the power turbine in a counter-rotating direction.

The fan blade of a ductless fan engine is
Variable pitch blades to ensure optimal performance is achieved. During operation, the fuel efficiency of the engine can be increased by changing the pitch of the blades to suit specific operating conditions.

In conventional systems, when attempting to change the pitch of a fan blade coupled to a rotating member disposed concentrically around a stationary member, the pitch is varied by a bearing arrangement coupled to a gearing arrangement. One such mechanism is described in pending US patent application Ser. No. 647,283, filed September 4, 1984. In that application, the pitch of a fan blade is varied by a hydraulic actuator mounted inside a stationary support structure of a power turbine. Motion from the actuator is first transmitted to the rotating member by a bearing system and then to the vanes by a system of gears and linkages attached to the rotating member. One disadvantage of using such a pitch changing mechanism may be the weight of the mechanism. When the engine is producing thrust, a large actuating force is required to maintain a particular pitch of the blades and to change the pitch of the propulsion blades. Since this actuation force must be transmitted to the vanes through the bearings, gears, and linkages, the bearings, gears, and linkages also have enough power to transmit this force without substantial deflection or deformation. Must have sturdiness. Any deflection or deformation of the mechanism will create play in the system, which will cause the fan blades to flutter a little as they rotate, and can also cause torsional imbalance in the engine. In order to make the mechanism sufficiently sturdy, its mass must be increased. As the weight of this mechanism is added to the rotating member,
The efficiency of the device may be adversely affected due to the increased inertia required to turn the rotating member. Another drawback of conventional blade pitch changing mechanisms appears to be the ease of access to the mechanism. Most of the mechanism is built into the stationary structure of the power turbine. To access this part, you must pass through a power turbine. Therefore, the location of the mechanism makes access and maintenance extremely difficult. Another drawback of conventional blade pitch changing mechanisms is believed to be the fatigue nature of the mechanism. The mechanism uses a plurality of racks connected to a plurality of corresponding pinion gears. By positioning the pinion gear with the rack, the pitch of the blades is changed. For any given rack and pinion, only a few gear teeth on the pinion mesh with a few teeth on the rack. Therefore, the entire force required to maintain a particular blade pitch must be supported by the teeth interlocking in this way. During normal flight and normal engine operation, the blade pitch angle remains relatively stable. Therefore, the few interlocking teeth mentioned above may fatigue and/or break, while the other teeth may experience little fatigue.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved device for changing the pitch of propulsion vanes in a ductless fan engine which overcomes the above-mentioned disadvantageous or undesirable features and other drawbacks of the prior art. It is to provide. Another object of the invention is to provide a device for changing the pitch of a vane that is relatively light in weight. Another object of the invention is to provide a device for changing the pitch of a vane that is easy to access. Another object of this invention is to provide an apparatus for varying the pitch of a vane such that the force to maintain a particular pitch of the vane is distributed over a number of gear teeth. These and other features, objects, and advantages of the invention will be apparent in part and will be apparent in part from the description that follows.

In one embodiment, the invention is directed to an apparatus for varying blade pitch in a propeller-driven gas turbine engine. The engine has a rotating structure and a plurality of variable pitch propulsion vanes extending radially outward from the rotating structure. The pitch of the blades is changed by a pinion gear coaxially coupled to one propulsion blade and an internal gear disposed radially around the pinion gear to drive the pinion gear. Angular displacement of the pinion gear relative to the rotating structure causes an angular displacement of the propulsion vanes relative to the rotating structure. An internal gear has more teeth than a pinion gear, and the teeth of the internal gear are sized to mesh with the teeth of the pinion gear.
Rotation of the internal gear around the pinion gear causes an angular displacement of the pinion gear with respect to the rotating structure.

Next, this invention will be explained with reference to the drawings. The same reference numerals are used throughout the drawings to refer to corresponding parts. Although the example described herein is one preferred embodiment of the invention, this illustration should not be construed as limiting the scope of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A ductless fan (UDF) is shown in FIGS. 1 and 2.
A jet engine 20 is shown. The engine has front and rear counter-rotating propulsion vanes 22, 24 located radially outwardly of a power turbine 25. Power turbine 25 includes first and second counter-rotating rotors 26, 28 and first and second counter-rotating turbine blades 30, 32 coupled to first and second rotors 26, 28, respectively. and has. Front and rear propellers 22, 24 are coupled to first and second rotors 26, 28, respectively, and rotate therewith. A first rotor 26 is disposed around the hollow stationary structure 34 and is rotatably connected to the stationary structure 34 by a first bearing 36 . A second rotor 28 is also arranged around the stationary structure 34 and is connected to the first rotor via a second bearing 38.
The rotor 26 is rotatably connected to the rotor 26 of the rotor 26. The outer shroud or nacelle 40 is the rotor 2
6 and 28, the propulsion blades 22 and 24 are attached to the nacelle 4.
It is arranged radially outward from 0. Nacelle 4
0 has a first sleeve 40a that is coupled to and rotatable with the front propulsion vane 22 and a second sleeve 40b that is coupled to and rotatable with the rear propulsion vane 24. It is possible. The purpose of the nacelle 48 is to
The objective is to provide appropriate air flow characteristics to optimize the performance of 2 and 24. Furthermore, the engine 20
It has an annular gas passage 42 formed to pass through the first and second rotors 26, 28. Air passing through engine 20 to gas flow path 42 is compressed and heated to form a high energy (high pressure/high temperature) gas stream generally indicated by arrow 44 .
This high-energy gas stream 44 flows through first and second rotors 26, 28 to rotate counter-rotating turbine blades 30, 32 and drive counter-rotating propulsion blades 22, 24, respectively.

To further optimize the performance of the ductless fan engine 20, it is desirable to vary the pitch of the propulsion vanes 22, 24. Each front propulsion vane 22
has a pitch varying axis 46, and each rear propulsion vane 24 has a pitch varying axis 48 about which the pitch of the vanes 22, 24 can be varied. To make the explanation easier to understand, only the pitch changing mechanism for the front propulsion blade 22 will be explained below. However, it goes without saying that a similar pitch changing mechanism can be used to change the pitch of the rear propulsion vanes 24.

Referring now generally to FIGS. 3-6, one type of apparatus of the present invention for varying the pitch of each propulsion vane 22 is illustrated. A blade root portion 50 fixed to the trunnion 52 extends radially inward from the propulsion blade 22. As best seen in FIG. 5, the trunnion 52 has an inverted V-shaped slot for receiving an inverted V-shaped extension that mates with that of the vane root 50. With trunnion 52 rotationally coupled to first rotor 26, angular displacement of trunnion 52, ie, rotation about the radius of engine 20, changes the pitch of vane 22. The pitch changing mechanism of the present invention includes a spur gear or binion 60 coaxially coupled to the trunnion 52, and an internal gear 64 disposed around the spur gear 60 in the radial direction and having more teeth than the pinion gear 60. and a mechanism for angularly displacing the spur gear 60 with respect to the radius of the engine 20 by rotating the internal gear 64 eccentrically around the spur gear 60, and the teeth of both the gears 60 and 64 are The dimensions are such that they fit together. Since the spur gear 60 is fixed to the root 50 of the blade, angular displacement of the spur gear 60 changes the pitch of the propulsion blade 22.

Next, referring to FIGS. 3 and 4 together with FIG. 2, the gear mechanism is shown in detail. A blade root 50 of the propulsion blade 22 is fixed to a trunnion 52. A trunnion 52 is mounted on a portion of the first rotor 26 using any suitable known roller bearing 5.
4 and a thrust bearing 56. Bearings 54 and 56 connect trunnion 52 to first rotor 26 such that trunnion 62 pivots or rotates relative to the radius of first rotor 26 to change the pitch of blades 22. . Spur gear 6
0 acts as a pinion, but trunnion 5
It is fixed to the base of 2 and is coaxial with it.
A rigid annulus 58 surrounds the spur gear 60. An internal gear or annular gear 64 is disposed on the inner surface 62 of the annulus 58 and rotates the spur gear 60. An internal gear or ring gear is, by definition, a gear that has gear teeth on its inner surface. Internal gear 64 has more teeth than spur gear 60, and the teeth on both gears are sized to mesh with each other. An internal gear 64 is eccentrically arranged around the spur gear 60 such that teeth on a portion of the internal gear 64 mesh with teeth on a corresponding portion of the spur gear 60. The internal gear 64 is the spur gear 60
rotates eccentrically about the rotating structure 26 to apply torque to the spur gear 60, thus causing the spur gear 60 to rotate relative to the rotating structure 26. By using an internal gear instead of a separate spur gear to rotate the spur gear 60, a large number of teeth mesh together, and the torque transmitted to the spur gear 60 is transmitted to the spur gear 60 rather than just a few teeth. Distributed over a large number of interlocking teeth. This reduces the stress and associated fatigue on each tooth. Although the internal gear 64 rotates eccentrically around the spur gear 60, the internal gear 64 does not rotate relative to the first rotor 26. Since spur gear 60 has fewer teeth than internal gear 64, each time internal gear 64 makes one complete revolution or orbit around spur gear 60,
The spur gear 60 advances or rotates relative to the internal gear 64 by the difference in the number of teeth between the internal gear 64 and the spur gear 60 . For example, assume that the internal gear has 74 teeth and the spur gear 60 has 72 teeth. During each orbital cycle of the internal gear 64, the 74 teeth of the internal gear 64 mesh with the corresponding teeth of the spur gear 60. Spur gear 6
Since 0 has two fewer teeth than internal gear 64, the two extra teeth of spur gear 60 mesh with the teeth of internal gear 64 on each orbit cycle. Therefore, the spur gear 60 advances or rotates relative to the internal gear 64 by two teeth. Spur gear 60 has 72 teeth, so each tooth is 5°. Therefore,
Advancement of two teeth corresponds to a rotation of 10°.

The reduction ratio between the internal gear 64 and the spur gear 60 is the internal gear 6 required to rotate the spur gear 60 by 360 degrees.
It can be defined as the number of orbital cycles of 4.
This reduction ratio is expressed by the following formula.

R = N _s / (N _i - N _s ) where R is the reduction ratio, N _s is the number of teeth of the spur gear 60,
N _i is the number of teeth of the internal gear 64. As is clear from this equation, when the spur gear 60 has slightly fewer teeth than the internal gear 64, the reduction ratio is large. Increasing the reduction ratio effectively increases the stiffness of the mechanism since a substantial movement of the internal gear 64 is translated into a small rotation of the spur gear 60 and the corresponding propulsion vanes 22. Furthermore, the greater the reduction ratio, the greater the number of teeth that mesh at the same time, and the greater the torque transmitted to the gears. Therefore, a large reduction ratio reduces overall fatigue of gears 60, 64.

4 to 6 show a mechanism for eccentrically rotating the internal gear 64 around the spur gear 60. An annulus 58 is slidably coupled to the first rotor 26 by suitable bearings 66. Furthermore, annular bodies 58 are connected to the first and second circular disk members 7, respectively.
Two circular cavities 6 dimensioned to receive 2,74
I have 8,70. first and second shafts 76,
78 are the first and second circular disk members 72, 7, respectively.
4, and both are rotationally coupled to first rotor 26 for rotation about their longitudinal axes, indicated by dashed lines 80 and 82 in FIG. Circular disk members 72, 74 are rotationally coupled to annulus 58 by suitable roller bearings 84, 86, such as needle and roller bearings. Since the shafts 76, 78 are eccentrically mounted to the circular disc members 72, 74, the shafts 76, 78 are aligned with their longitudinal axes 80, 8.
When rotated simultaneously around 2, the circular disk member 7
2, 74 rotates eccentrically. Circular members 72, 7
The eccentric rotation of 4 moves each point on the annulus 58 along a circular path, thus rotating the internal gear 64 about the spur gear 60. Circular members 72, 74
The eccentricity of is equal to the eccentricity of the internal gear 64 around the spur gear 60, and the eccentric rotation of the circular members 72 and 74 causes the teeth to mesh between the spur gear 60 and the internal gear 64. It is preferable to do so. Circular member 7
If the eccentricity of 2,74 is greater than the eccentricity of the internal gear 64, the teeth will be jammed. Circular members 72, 74
If the eccentricity of
A slip occurs between 0 and 64. By eccentrically rotating the two circular members 72 and 74 instead of just one, the ring 58 is rotated around the first rotor 26.
It rotates around the spur gear 60 without any angular displacement relative to it. Furthermore, the eccentricity of the disc-shaped members 72, 74 must be synchronized to prevent the disc-shaped members 72, 74 from catching on the annulus 58.

Simultaneous rotation of the circular members 72, 74 is accomplished by a drive shaft 96 coupling the two circular members 72, 74 together. First and second shafts 76, 78 project from the first rotor 26 and are connected to first and second bevel gears 88, 90, respectively.
terminates in first and second bevel gears 88, 90 engage third and fourth bevel gears 92, 94, respectively;
A drive shaft 96 is rigidly connected to third and fourth bevel gears 92,94. Drive shaft 96 and corresponding bevel gears 88, 90, 92, 94 rotate one circular member 72, 74 as the other circular member 72, 74 rotates. Therefore, the drive shaft 9
6 about its longitudinal axis causes circular members 72, 74 to rotate synchronously and eccentrically.
Preferably, rotation of the drive shaft 96 is effected by a motor 98 coupled to the fourth bevel gear 94, such as a hydraulic motor or an electric motor. That is, the pitch changing mechanism of the present invention effectively converts the rotational movement of the motor 98 into a movement for changing the pitch of the propulsion blades 22. If the corresponding bevel gears have the same number of teeth, the reduction ratio between the drive shaft 96 and the spur gear 60 is the same as the reduction ratio between the internal gear 64 and the spur gear 60. When the reduction ratio is large, it is necessary to rotate the drive shaft 96 significantly about its longitudinal axis in order to slightly change the pitch of the propulsion blades 22. Therefore, variations in blade pitch due to play or backlash between corresponding bevel gears can be ignored. It is preferable that each propulsion blade 22 be provided with a blade pitch mechanism as described above to change the pitch of each blade 22. Furthermore, the well-known universal joint 100
By combining the drive shafts of adjacent blade pitch mechanisms,
The rotation of each drive shaft is synchronized, and thus the pitch of all propulsion vanes is synchronized. If a large reduction ratio is used between the corresponding drive shaft and spur gear, the play between the drive shafts has virtually no effect on the pitch angle of the blades and does not affect the synchronization of the pitch of the blades.

As shown in FIG. 2, the pitch changing mechanism of the present invention is located adjacent to the blade root 50 and outside the gas flow path 42. Locating the mechanism in this manner provides greater accessibility since it is not necessary to enter the power turbine to service the mechanism. This minimizes the time and/or cost of servicing the mechanism.

Having clarified the idea of the invention by way of example, those skilled in the art will be able to determine without departing from this idea the structure, arrangement, arrangement, etc. used to carry out the invention as appropriate for particular operating conditions. Various modifications to the parts and components may be easily envisaged. Therefore, the above description is illustrative of this invention and should not be construed as limiting this invention.
It is to be understood that the invention is limited only by the scope of the claims that follow.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a ductless fan type gas turbine engine, Fig. 2 is a side sectional view of the turbine section of the ductless fan type gas turbine engine, and Fig. 3 is an enlarged sectional view of Fig. 2. The propulsion vanes are shown coupled to the structure. FIG. 4 is a plan view of the internal gear surrounding the spur gear, FIG. 5 is a perspective view of the blade pitch changing mechanism of the present invention, and FIG. 6 is a front sectional view of the bevel gear and universal joint device of the present invention. Explanation of main symbols, 22, 24... Propulsion blade, 2
6, 28... Rotor, 30, 32... Turbine blade, 34... Stationary structure, 58... Annular body, 60...
Pinion gear, 64... Internal gear, 96... Drive shaft.

Claims (1)

[Scope of Claims] 1. An immovable member; first and second rotating members disposed coaxially around the immovable member; and an annular gas flow path coaxial with the first and second rotating members. and attached to the first and second rotating members, respectively, so that the first and second rotating members rotate in opposite directions by the gas flow that enters the flow path and passes through the flow path. a plurality of first and second
rotor blades; a plurality of front and rear variable pitch propulsion blades disposed radially outward from the first and second rotating members and coupled to them, respectively; coaxially with one of the propulsion blades; are combined,
a driven gear that causes a pitch change of the propulsion blades to be effected by an angular displacement of the driven gear with respect to a radius of the rotating member; a driving gear coupled to the driven gear; and a driving gear coupled to the driven gear; and means for causing the driven gear to angularly displace in response to the driving gear to change the pitch of the blades by rotating eccentrically relative to the driven gear, one of the driven gear and the driving gear. is an internal gear, the other of the driven gear and the drive gear is a pinion gear, the internal gear is eccentrically arranged around the pinion gear, and has a greater number of teeth than the pinion gear. In most gas turbine engines, the dimensions are such that the teeth of both the internal gear and the pinion gear mesh with each other. 2. The gas turbine engine according to claim 1, wherein the driven gear constitutes the pinion gear, and the driving gear constitutes the internal gear. 3. The gas turbine engine according to claim 2, comprising means for preventing angular rotation of the internal gear with respect to the radius of the rotating member. 4. In the gas turbine engine according to claim 2, the rotating means includes: a first circular member coupled to the rotating member; and a biasing of the first circular member with respect to the rotating structure. A gas turbine engine comprising: means for rotating the first circular member about its center; and means for converting eccentric rotation of the first circular member into rotational movement of the internal gear about the pinion gear. 5. The gas turbine engine according to claim 4, further comprising means for preventing angular rotation of the internal gear with respect to the rotating member. 6. The gas turbine engine according to claim 5, wherein the internal gear is provided on the inner surface of a sturdy ring body. 7. The gas turbine engine according to claim 6, wherein the converting means is within the annulus and has a first circular cavity dimensioned to receive the first circular member. Therefore, by eccentric rotation of the first circular member with respect to the rotating member, each point on the ring body moves along a circular path, causing the internal gear to rotate around the pinion gear. gas turbine engine. 8. In the gas turbine engine according to claim 7, the means for eccentrically rotating the first circular member is rotatably coupled to the rotating member, and the rotating member rotates about the longitudinal axis of the shaft. The first circular member has a shaft that can rotate relative to the rotating member, and the first circular member is eccentrically fixed to the shaft, so that rotation of the shaft relative to the rotating member causes the first circular member to rotate relative to the rotating member. A gas turbine engine, wherein the eccentrically rotating means includes motor means coupled to the shaft for rotating the shaft. 9. The gas turbine engine according to claim 8, wherein the motor means is constituted by a fluid pressure motor. 10. In the gas turbine engine according to claim 7, the means for preventing angular rotation of the internal gear with respect to the rotating member includes: a second circular cavity in the annular body; a second circular member within the circular cavity and eccentrically coupled to the rotating member such that the eccentricity of the second circular member substantially corresponds to the eccentricity of the first circular member; and means for synchronizing the rotation of the first circular member with the relative rotation of the second circular member. 11. The gas turbine engine according to claim 10, which has means for synchronizing the pitches of all propulsion blades. 12. The gas turbine engine according to claim 10, which includes blade pitch changing means coupled to each propulsion blade. 13. A gas turbine engine according to claim 12, which includes means for synchronizing the pitches of all propulsion blades. 14 a stationary member, a rotating structure coaxially disposed around the stationary member, an annular gas flow path coaxial with the rotating structure, coupled to the rotating structure and entering the gas flow path; a plurality of rotor blades for rotating the rotating structure relative to the stationary member by a gas flow flowing through the rotor blades; and a plurality of variable pitch blades arranged radially outwardly of the rotating structure and coupled to the rotating structure. In a gas turbine engine having propulsion blades, a driven gear coaxially coupled to one propulsion blade is provided in a means disposed radially outward from the annular gas flow path for changing the pitch of the propulsion blade. angular displacement of the driven gear relative to the rotating structure causes the propulsion vane to be angularly displaced relative to the rotating structure; further comprising a drive gear coupled to the driven gear; One of the gear and the driving gear is an internal gear, the other of the driven gear and the driving gear is a pinion gear, and the internal gear is eccentrically arranged around the pinion. It has a larger number of teeth than the pinion gear, and is sized so that the teeth of both the internal gear and the pinion gear mesh with each other, and further includes means for eccentrically rotating the drive gear with respect to the driven gear. means for changing the pitch of the propulsion vanes, the driven gear being angularly displaced relative to the rotating structure; 15. In the means for changing the pitch of the propulsion blades set forth in claim 14, the driven gear constitutes a pinion gear, and the driving gear constitutes an internal gear, and the pitch of the propulsion blades is changed. means. 16. In the means for changing the pitch of the propulsion vanes as set forth in claim 15, the means for changing the pitch of the propulsion vanes includes means for preventing angular rotation of the internal gear with respect to the rotating structure. 17. In the means for changing the pitch of the propulsion blades as set forth in claim 15, the means for rotating the driving gear comprises: a first circular member coupled to the rotating structure; and a first circular member coupled to the rotating structure. a propulsion vane comprising: means for eccentrically rotating the first circular member; and means for converting the eccentric rotation of the first circular member into rotational movement of the internal gear about the pinion. Means to change pitch. 18. The means for changing the pitch of the propulsion vanes as set forth in claim 17, wherein the means for changing the pitch of the propulsion vanes includes means for preventing angular rotation of the internal gear with respect to the rotating structure. 19. The means for changing the pitch of the propulsion vanes as set forth in claim 18, wherein the internal gear is on the inner surface of a rigid annulus. 20. The means for changing the pitch of propulsion vanes as set forth in claim 19, wherein the means for changing comprises a first circular cavity in the annulus dimensioned to receive the first circular member. so that when the first circular member rotates eccentrically with respect to the rotating structure, each point of the ring moves along a circular path, thus moving the internal gear around the pinion gear. Means to change the pitch of the propulsion blades to be rotated. 21. In the means for changing the pitch of the propulsion blades according to claim 20, the means for eccentrically rotating the first circular member is rotatably coupled to the rotating structure, and the longitudinal axis of the shaft a shaft rotatable relative to the rotating structure around the rotary structure; and motor means coupled to the shaft for rotating the shaft, the first circular member being eccentrically fixed to the shaft. means for changing the pitch of a propulsion vane in which the first circular member rotates eccentrically with respect to the rotary structure as the shaft rotates with respect to the rotary structure. 22. The means for changing the pitch of the propulsion blades as set forth in claim 21, wherein the motor means is a fluid pressure motor. 23. In the means for changing the pitch of the propulsion vanes as set forth in claim 21, the means for preventing angular rotation of the internal gear with respect to the rotating structure comprises a second circular cavity in the annular body; , a second circular member located within the second cavity and eccentrically coupled to the rotating structure, the eccentricity of the second circular member being approximately equal to the eccentricity of the first circular member;
a circular member; and means for synchronizing rotation of said first circular member with relative rotation of said second circular member. 24. In the means for changing the pitch of the propulsion blades as set forth in claim 23, the means for changing the pitch of the propulsion blades includes means for synchronizing the pitches of all the propulsion blades. 25. In the means for changing the pitch of the propulsion blades as set forth in claim 23, means for changing the pitch of the propulsion blades in which each propulsion blade is combined with a means for changing the pitch of the blades. 26. In the means for changing the pitch of the propulsion blades as set forth in claim 25, the means for changing the pitch of the propulsion blades includes means for synchronizing the pitches of all the propulsion blades. 27. In a gas turbine engine having a rotating structure and a plurality of variable pitch propulsion blades extending radially outward from the rotating structure, the means for changing the pitch of each blade may include a driven gear coupled such that rotation of the driven gear with respect to a radius of the rotating structure changes the pitch of a corresponding propulsion vane; and a drive operatively coupled to the driven gear. a gear; and means for eccentrically rotating the driving gear with respect to the driven gear, one of the driven gear and the driving gear is an internal gear, and the other of the driven gear and the driving gear is an internal gear. is a pinion gear, and the internal gear is eccentrically arranged around the pinion, has more teeth than the pinion gear, and has dimensions such that the teeth of both the internal gear and the pinion gear mesh with each other. It's getting old,
Means for changing the pitch of the blades, the driven gear being angularly displaced relative to the radius of the rotating structure in response to eccentric movement of the driving gear. 28. The means for changing the pitch of blades according to claim 27, wherein the driven gear constitutes a pinion, and the driving gear constitutes an internal gear. 29. The means for changing the pitch of the blades as set forth in claim 28, which includes means for preventing angular rotation of the internal gear with respect to the rotating structure. 30. In the means for changing the pitch of blades as set forth in claim 28, the means for rotating the driving gear comprises: a first circular member coupled to the rotating structure; and a first circular member coupled to the rotating structure. changing the pitch of a vane, comprising means for eccentrically rotating a first circular member; and means for converting eccentric rotation of the first circular member into rotational movement of the internal gear about the pinion; means to do. 31. The means for changing the pitch of the blades as set forth in claim 30, which includes means for preventing angular rotation of the internal gear with respect to the rotating structure. 32. The means for changing the pitch of the blades as set forth in claim 31, wherein the internal gear is on the inner surface of a rigid ring. 33 In the means for changing the pitch of the blades set forth in claim 32, the converting means comprises:
a first circular cavity within the annulus and dimensioned to receive the first circular member;
Eccentric rotation of the first circular member relative to the rotating structure causes points on the annulus to move along a circular path, thus changing the pitch of the vanes that rotate the internal gear about the pinion. means to do. 34. In the means for changing the pitch of the blades set forth in claim 33, the means for eccentrically rotating the first circular member is rotatably coupled to the rotating structure, and the means for eccentrically rotating the first circular member is rotatably coupled to the rotating structure, and a shaft rotatable relative to the rotating structure; and motor means coupled to the shaft for rotating the shaft, the first circular member being eccentrically fixed to the shaft. means for changing the pitch of the blades at which the first circular member rotates eccentrically relative to the rotating structure when the shaft rotates relative to the rotating structure. 35. The means for changing the pitch of the blades as set forth in claim 34, wherein the motor means is constituted by a fluid pressure motor. 36. In the means for changing the pitch of blades as set forth in claim 34, the means for preventing angular rotation of the internal gear with respect to the rotating structure comprises a second circular cavity in the ring body; within the second cavity and eccentrically coupled to the rotating structure such that the eccentricity of the second circular member is substantially equal to the eccentricity of the first circular member. Means for changing the pitch of a vane, comprising: a second circular member; and means for synchronizing the rotation of said first circular member with the relative rotation of said second circular member. 37. In the means for changing the pitch of the blades as set forth in claim 36, the means for changing the pitch of the blades includes means for synchronizing the pitches of all propulsion blades. 38. In the means for changing the pitch of the blades as set forth in claim 36, means for changing the pitch of the blades connected to each propulsion blade. 39. In the means for changing the pitch of the blades as set forth in claim 38, the means for changing the pitch of the blades includes means for synchronizing the pitches of all propulsion blades.